Vulnerability Description
frp is a fast reverse proxy. From 0.53.0 until 0.70.1, frp's optional SSH Tunnel Gateway in pkg/ssh/server.go parses an SSH exec channel request by adding 4 to an attacker-controlled four-byte big-endian length. A length of 0xFFFFFFFF makes the uint32 addition wrap to 3, defeats the payload bounds check, and causes payload[4:3] to panic in TunnelServer.handleNewChannel. When no authorized-keys file is configured, sshConfig.NoClientAuth permits an unauthenticated peer to reach this channel phase before the frp token is checked, so a single five-byte request terminates the frps process and drops every active tunnel. This issue is fixed in version 0.70.1.
Related Weaknesses (CWE)
References
- https://github.com/fatedier/frp/commit/7dc7be930e2452ae93fd32f2a77f8c6fcd0b652b
- https://github.com/fatedier/frp/pull/5428
- https://github.com/fatedier/frp/releases/tag/v0.70.1
- https://github.com/fatedier/frp/security/advisories/GHSA-26gq-p25f-99cp
- https://github.com/fatedier/frp/security/advisories/GHSA-26gq-p25f-99cp
FAQ
What is CVE-2026-73564?
CVE-2026-73564 is a documented vulnerability. frp is a fast reverse proxy. From 0.53.0 until 0.70.1, frp's optional SSH Tunnel Gateway in pkg/ssh/server.go parses an SSH exec channel request by adding 4 to an attacker-controlled four-byte big-end...
How severe is CVE-2026-73564?
CVSS scoring is not yet available for CVE-2026-73564. Check NVD for updates.
Is there a patch for CVE-2026-73564?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.